沿海湿地生态系统服务外文文献翻译.docx
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沿海湿地生态系统服务外文文献翻译
标题:
沿海湿地生态系统服务
英文
Forecastingecosystemservicestoguidecoastalwetlandrehabilitationdecisions
RyanS.D.Calder,CongjieShi,SaraA.Mason,
LydiaP.Olander,MarkE.Borsuk
Abstract
Coastalwetlandsprovidediverseecosystemservicessuchasfloodprotectionandrecreationalvalue.However,predictingchangesinecosystemservicevaluefromrestorationormanagementischallengingbecauseenvironmentalsystemsarehighlycomplexanduncertain.Furthermore,benefitsarediverseandaccrueovervarioustimescales.WedevelopedageneralizablemathematicalcoastalmanagementmodeltocomparerestorationexpenditurestoecosystemservicebenefitsandapplyittoMcInnisMarsh,MarinCounty,California,USA.Wefindthatbenefitsofrestorationoutweighcostsforawiderangeofassumptions.Forinstance,costsofrestorationrangefrom8–30%oftheincreaseinecosystemservicevalueover50 yearsdependingondiscountrate.Floodprotectionisthedominantmonetizedserviceformostpaybackperiodsanddiscountrates,butotherservices(e.g.,recreation)dominateonshortertimescales(>50%oftotalvalueforpaybackperiods≤4 years).Wefindthattherangeoftotalecosystemservicevalueisnarrowerthanoverallvariabilityreportedintheliterature,supportingtheuseofmechanisticmethodsindecision-makingaroundcoastalresiliency.However,themagnitudeandrelativeimportanceofecosystemservicesaresensitivetopaybackperiod,discountrateandrisktolerance,demonstratingtheimportanceofprobabilisticdecisionanalysis.Thisworkprovidesamodular,transferrabletooltothatcanalsoinformcoastalresiliencyinvestmentselsewhere.
Keywords:
Ecosystemservices,Economicvaluation,Environmentalmodeling,Coastalwetlands,Climateadaptation,Decisionanalysis
1. Introduction
Coastalwetlandsareincreasinglyrecognizedasmultifunctionalenvironmentsthatprovidediverseservicessuchasfloodprotection,urbanwaterfiltrationandnestingandbreedinghabitatforkeyspecies(Aertsetal.,2014, Costanzaetal.,2008, Yangetal.,2017).Thehydrologicfunctionofwetlandsisthemostwidelycited,andreclamationanddevelopmentofwetlands(particularlyinfloodplains)havegreatlyincreasedthemagnitudeofflooddamagesintheUnitedStatessincecolonialtimes(AcremanandHolden,2013, HeyandPhilippi,1995).However,policy-makersandenvironmentalinterestgroupsareincreasinglyviewingwetlandrestorationandconservationastoolstopreserveandenhancediverseecological,recreationalandotherfunctions.Forexample,intheSanFranciscoBayarea,>85%ofhistoricaltidalmarshareahasbeendiked,filledorotherwiselost,endangeringpopulationsofmigratorybirdswhoroostandforagethere(USGS,2018).Thebenefitstothesekeyspeciesarecommonlycitedjustificationsforwetlandrestorationinitiatives(e.g., SouthBaySaltPondRestorationProject,2015).Coastalwetlandsthereforeprovidediverseservicestodiversestakeholders,andtheseservicesaccrueindifferentunitsoverdifferenttimescales.This,togetherwiththevariabilityanduncertaintyinherentinenvironmentalsystems,presentsachallengetodecision-makerswhomustweightheseprospectivefuturebenefitsagainstcostsofrestorationorpreservation.
Thereexistmultipleframeworkstocalculateecologicalvalueofland-usescenarios,buttheirutilityindecision-makinghasbeenlimitedbynarrowscopeandpoorsupportforprospectiveanalysis. Grêt-Regameyetal.(2017) identify68uniqueecosystemservicevaluationtools,ofwhichthemostcomprehensiveandwidelycitedisthe IntegratedValuationofEcosystemServicesandTradeoffs (InVEST)model(Sharpetal.,2018).Thesetoolscouplebiophysicalandeconomicmodelsandcancontributetothepolicyprocessbyestimatingbenefitsassociatedwithalternativeland-useassumptions(Goldsteinetal.,2012).However,existingtoolstendtofocusonasmallsubsetofecosystemservices(deGrootetal.,2010, Grêt-Regameyetal.,2017)andmostlydonotcharacterizethelargeparameterspacecharacteristicofunknown,alternativestatesofcomplexenvironmentalsystems(HamelandBryant,2017).Conversely,widevariabilityinretrospectiveecosystemservicevaluationshaslimitedtheutilityoflandcover-basedbenefits-transferapproaches.Forexample,inthecaseofwetlands,totalecosystemservicevaluemayrangefrom<2$ha−1 yr−1 to>340000$ha−1 yr−1 (2017-$),dependingonhighlysite-specificfactorssuchasthevalueofavoidedfloodsandthepotentialforconservationofvulnerablespecies(Branderetal.,2006).Overall,ithasbeenpoorlyunderstoodwhetherprospectiveecosystemservicemodelscannarrowtheseuncertainties,andthishaslimitedtheinterpretabilityofmodeloutputsbydecision-makers(HamelandBryant,2017).
Ourpreviousworkhasdemonstratedthatcontrollingforuncertaintiesthatarecorrelatedacrosspolicyalternativescansubstantiallyincreaseconfidenceinvaluationsofproposedinterventions(ReichertandBorsuk,2005).Isolatinguncertaintiesassociatedwithhypotheticalenvironmentalchangesfromthebaselineuncertaintiesinherenttoenvironmentalsystemshoweverrequiresthatanalysisbecarriedoutwithinintegratedprobabilisticenvironmentsor“wrappers”,afacilitynotsupportedbycommonlyusedoff-the-shelfecosystemservicevaluationtools(HamelandBryant,2017).Indeed,availabletoolstendtomakeuncertaintyanalysisatime-consumingprocess,anditisfrequentlyneglectedinpractice:
Seppeltetal.(2011) foundthatonlyonethirdof460studiescarriedoutevenbasicuncertaintyanalysis.Emerginggraphicalmethodsknownvariouslyas“resultschains”(Tallisetal.,2017),“logicmodels”(CDC,2010)and“Bayesiannetworks”(Pearl,1995)arewell-suitedtofacilitatequantitativemodelingthattrackscorrelationsofuncertainvariables.Previously,wehavedemonstratedhowthesetechniquescanbeusedtoencodeinteractingbiophysicalpathwaysbetweenenvironmentalpolicydecisionsandecosystemservicesofrelevancetostakeholdersintermsofavailabledataandmodelingcapacity(Borsuketal.,2001, Borsuketal.,2012, MasonandOlander,2018).
Recentupdatestofederalguidelinesforenvironmentalprojects,riskmanagement,andnaturalresourcemanagementrequireexplicitcharacterizationofecosystemservicevalueofpolicyalternatives(CouncilonEnvironmentalQuality(CEQ),2014, FederalEmergencyManagementAgency(FEMA),2016, Olanderetal.,2018, UnitedStatesForestService,2012).Therefore,methodstoimproveforecastingandbenefitsmodelingareurgentlyneeded.Managementofcoastalwetlandspresentsaparticularlyimportantresearchareagiventheincreasingattentiontheseenvironmentsarereceivinginternationally(Barbier,2013, Yangetal.,2017)andthepoorlycharacterizedconceptualgapsbetweenbiophysicalconditionsandsociallyvaluedoutcomes(Boydetal.,2015).WeproposethatstructuringenvironmentalpolicyquestionswithinaBayesiananalyticalgraphicalmodelingframeworkhasthepotentialtoimprovedecision-makingbynarrowingandrobustlyassessinguncertainties.Inparticular,methodsthattrackcorrelateduncertaintiesmayprovideamorerobustquantificationofbenefitsofpolicyalternativesinhighlycomplexandvariableenvironmentssuchascoastalwetlands.
Here,wesynthesizecurrentscientificunderstandingofthebiophysicalpathwaysbetweencoastalrestorationandecosystemserviceendpointsintoaquantitative,probabilisticmodel.UsingacasestudyfromtheSanFranciscoBayarea,California,USA,weevaluatehowrisktoleranceanddiscountrateinteractwithmodeluncertaintiesandnon-stationaritiestodeterminepolicyoptima.ThisworkcanbeeasilytransferredtoothersitesintheSanFranciscoBayestuary,whereecosystemservicesarelikelytobesimilarandwherewetlandrestorationandconservationhavebecomeenvironmentalmanagementpriorities(USGS,2018).Morebroadly,thisworkevaluateshowmechanisticallyexplicitmodelscaninformdecisionsinthehighlycomplexanduncertainsettingofcoastalwetlands.Finally,wearguethatpolicyinterpretabilityofbiophysicalandeconomicmodeloutputisdependentonconsiderationofdecision-analyticparameterssuchasdiscountrate,paybackperiodandrisktolerance.Thispointstotheimportanceofstructuringsuchanalysiswithinprobabilistic,decision-analyticenvironments.
2. Methods
Wepresentadecisionanalyticframeworktoreconcileuncertainfuturecostsandecosystemservicebenefitsassociatedwithalternativemanagementdecisionsforcoastalmarshenvironments.Tocapturetheuncertaintiesinmodelformulations,wenestbiophysicalandeconomicmodelswithinaprobabilisticMonteCarloframework.Inpreviouswork,wedevelopedgeneralandsite-specificconceptualmodelsforecosystemserviceimpactsofcoastalmanagementinterventions(Section2.1).Here,weextendthesite-specificconceptualmodeldevelopedfortheMcInnisMarshrestorationproject,MarinCounty,California,USA(Section2.2),byreplacingconceptualrelationshipswithquantitativebiophysicalandeconomicmodels.
Ourintegrativeframeworkallowsmanagementscenariostobecomparedintermsofprobabilisticallydistributedfuturecostsandbenefitscorrespondingto
(1)waterqualityimprovements;
(2)reducedrain-drivenflooding;(3)improvedrecreationalvalue;(4)enhancedspeciesabundance;and(5)carbonsequestration,incomparisonwithrecurringandupfrontmanagementcosts(e.g.,creekdredging).Wequantifytheimpactofdecision-makerpreferencesandvalues(paybackperiod,discountrateandrisktolerance)oneconomicvaluationsandexploretherolethesemayhaveindecision-making.
2.1. Conceptualmodeldevelopment
Inpreviouswork,wedevelopedaconceptualmod